[Elecraft] K3S Audio buzz on transmit, especially AM

[Rick WA6NHC]

What they are saying is that it is best to break things down into 
logical clear steps, isolating as much as possible to prove or eliminate 
cause and effect.  The issue are that some folks don't know enough to do 
this and some have issues trying to be logical; running in circles while 
others often seek the easy way(s) out. No slur is meant or intended, 
people have different abilities or we wouldn't need groups like this.

This is all best done while the XYL is at the spa or otherwise 
unavailable for a few hours.  ;-)

Here is one example for your situation:

A critical and valid test to find the source of your radio problem is to 
run the radio on battery (no solar, no other wiring including ground) 
into a dummy load (completely isolated from everything, including any 
metal table that might be in use) with the house mains (and any 
outbuildings) turned completely OFF.  Set up the test receiver in the 
same manner (nothing but different battery for power and another dummy 
load).

This is to determine if it's the radio or the home environment (no stray 
induction).  If everything is clean, it's probably not the radio but to 
make sure...

The second portion of that test would be to repeat on different bands or 
frequencies within the band to eliminate 'fundamental overload'  or 
unexpected mixing of the receiver (which should also be on a dummy load, 
proximity is likely enough to hear the signal).  Is it band related or 
single band, on one frequency only or all?  At only certain output power 
levels (bad internal amp?  A 100 watt K3 has a series of three amps)?  
If the radio is clean, skip the next step.

The third step (if the problem still exists) is to provide physical 
isolation of the receiver (another room even if both are on dummy loads) 
to note any changes (overload or coupling is no longer likely).  If the 
problem remains, it's a radio issue (don't discount a receiver issue so 
you can confirm the issue with a second receiver).

Then based on these results, if it's all clean, (therefore not a radio 
issue so more testing is required to find the actual cause) one then 
determines a potential cause as you re-power the house (breaker by 
breaker).  In other words, when does it return?

In the best case, flipping only one breaker on, testing, turning that 
breaker off and moving to the next breaker; then bringing multiple 
breakers on in combinations (interaction of home devices?).  At which 
point/s does the issue return?  Single breaker means examine everything 
powered on that circuit, mixed breakers is much more of a challenge to 
find the cause.  Recall that house wiring often appears 'random' so it 
may be a challenge to find what each circuit powers.

If the problem doesn't return with turning on all the breakers, the 
search continues.

Note changes as you reconnect to the rest of the world (add antennas, 
control cables, etc) to your station.  Through more testing, at which 
point does the issue return?

Then reset all the clocks in the house as you ponder the results.

With an antenna connected, this series of tests also gives you a good 
baseline for RF noise reduction if the home generates noise (it's 
guaranteed that it will).

In your case, just for giggles, make SURE that ALL the tmp connectors in 
the K3(s) are properly connected as well (re-seat them) and re-tighten 
all screws and bolts as well (Murphy lives). While it's opened up, make 
sure no case paint is in the way of any bonding too, no corrosion, 
roaming parts etc. and look for obvious failures (disconnected wires, 
frays or pinched wire all without the smell of escaped smoke).

And lastly, a complete reset (groan) is an option, sometimes things are 
not what they show to be or are expected to be (stuck bits, EEPROM 
belches...).  Made when the radio is functioning correctly, you DO have 
a current backup of settings to use, no? If not, you manually make what 
changes are required (MANY of them, hence the groan) THEN make a backup.

Now if there is a need to call for further assistance (Elecraft help 
line, your Elmer or here), one has (dis)proven some of the possibilities 
to present the issue.

While others may disagree in this content, this is but one path to follow.

GL,
Rick nhc

On 4/27/2019 11:31 AM, Nicklas Johnson wrote:
> I don't think that "collecting data" and "process of elimination" are
> particularly ANTI-methodical either.  But the fact is that most people will
> never encounter this kind of problem and don't spend their days practicing
> how to troubleshoot it, so they seek advice from people who do have
> experience.  Thus this email thread, which began with my thinking I'd
> developed an audio fault in the rig and seeking advice, but successive
> tests have pointed in other directions.
>
> To answer Jim's earlier question, yes, it does appear that transmitting an
> unmodulated AM carrier from the K3S into anything resembling an antenna
> yields a buzz on the KX3 receiver (and vice-versa).  The buzz is NOT
> audible when listening to the K3S's own TX monitor.
>
> And to answer Frank's question, the PG&E transformer in our front yard for
> the underground utilities is approximately 30 horizontal feet over and 6
> vertical feet down from the station.  The distance to the utilities that
> run through the back of our lot is approximately 60 feet.
>
> I spent the morning reviewing (again) materials on grounding and bonding
> over my morning coffee to see if there's something important I missed, and
> I also found by repeating it that an earlier test I'd done had given me a
> misleading/contradictory result-- transmitting into a dummy load
> immediately adjacent the KX3 receiving it produces a nice, clean signal.  I
> was misled before by the KX3 picking up a different buzz (probably off a
> wall wart) in the shack when performing this test earlier.  (It also helped
> in this case to put the KX3 into CW mode to detect the unmodulated AM
> carrier.)
>
> FWIW, this morning I also disconnected the bonding between the station's
> ground rod and the house's utility power and also disconnected the DTV
> antenna run into the house (which shares the same coax grounding/surge
> protection bus outside, but of course could find another path to ground
> over the coax shield via either one of the TV receivers).  Doing so
> eliminated any *direct * connection with the utility power, as I'm still
> running purely on battery power.  This had NO effect on the received buzz.
>
> At this point I'm pretty sure this is an environmental issue and not a
> problem with either rig, so it's probably not appropriate for me to
> continue to pester the list about it.  Thank you again to everyone who
> offered suggestions and advice.
>
> But for posterity, and in case anyone comes along searching the list while
> debugging a similar problem, here's a list of all the other things that I
> tried to isolate the problem, none of which had any effect:
>
>     - Complete disconnection of all other inputs and outputs on the K3S
>     other than the antenna.
>     - Turning off all nearby power supplies.
>     - Setting the input to any other selection (front panel, rear panel,
>     line in)
>     - Setting the line input level to 0, verifying that front and rear panel
>     gains were set to "low"
>     - Running solely on battery power without the solar charge controller
>     - TX EQ settings- cutting the low end completely
>     - Taking the receiver outdoors, away from power supplies
>     - Trying a different transmit antenna (ie, making sure I wasn't having
>     problems with a damaged dipole having the house neutral wiring as one leg)
>     - Temporarily disconnecting the station ground
>     - Temporarily disconnecting the utility bonding from the station's
>     ground rod
>     - Reversing the direction: transmitting with the KX3 into a portable
>     antenna and receiving with the K3S also produced a much more significant
>     buzz
>
> What DID yield some useful data:
>
>     - Transmitting into a dummy load *while* turning off all nearby power
>     supplies and lights with the KX3 immediately adjacent the dummy load: nice,
>     pristine signal
>     - Checking the TX monitor on the K3S: only white noise with the line
>     input and the monitor output turned to maximum while transmitting.
>
> What I have yet to do, and will require some more time and effort to
> organize and implement:
>
>     - Going portable or to another QTH to test again
>     - Getting a signal report from a distant station to see if this is a
>     local reception problem, or something actually getting into the transmitted
>     signal.
>
>
>     Nick
>